Image capture unit and computer readable medium used in combination with same

ABSTRACT

An image capture unit and computer readable medium used in combination therewith is disclosed. In a preferred embodiment, the image capture unit includes an image capturing sensor, a visual display, an instance of the computer readable medium, and circuitry for integrating functionalities thereof. The computer readable medium causes sensor data received from the image capturing sensor to be processed. The sensor data includes a plurality of image tiles and position indicating data defining a respective relative position of each one of each image tiles. Each one of each image tiles includes data representing a discrete portion of visual content. The computer readable medium causes a feedback image be displayed on the visual display. Displaying the feedback image includes correlate the relative position of each one of each image tiles with at least one other image tile that has previously generated and displayed.

CROSS REFERENCE TO RELATED APPLICATIONS

This continuation patent application claims priority from U.S.Non-provisional patent application having Ser. No. 12/590,725, filed 13Nov. 2009, entitled “HANDHELD SCANNER AND SYSTEM COMPRISING SAME”, whichclaims priority from U.S. Provisional Patent Application having Ser. No.61/199,467, filed 17 Nov. 2008, entitled “HANDHELD SCANNER AND METHOD”,both having a common applicant herewith and being incorporated herein intheir entirety by reference.

FIELD OF THE DISCLOSURE

This invention generally relates to digital scanners and other types ofimage capture units and more specifically to a handheld image captureunit.

BACKGROUND

Document and image scanners are pervasive in the modern digital world.They are used to digitize documents and images (e.g., pictures) so thatthey can be used electronically. One of the most common types of scanneris the fax machine. A physical document such as, for example, a typeddocument or picture, is fed into the scanner where it is automaticallymoved across a sensor to digitize visual content (e.g., printed text,illustrations, photo, etc) provided on the surface of the physicaldocument, thereby creating a digitized image of the visual content. Thedigitized visual content image is then sent over a communication networkto another fax machines that prints a representation of the digitizedvisual content image. A physical document is one example of a scannableobject.

Another common type of scanner is the flatbed scanner, which istypically connected to a computer. A physical document is placed onto aglass imaging surface (commonly referred to as a platen) of the flatbedscanner and, once activated, the flatbed scanner automatically scans thevisual content of the physical document, thereby creating a digitizedimage of the visual content. The digitized visual content image can thenbe sent the computer for allowing a user to view and/or use thedigitized visual content image for any one of a number of purposes.Examples of such purposes include, but are not limited to, printing thedigitized visual content image, editing the digitized visual contentimage, converting the digitized visual content image into an electronictext document using optical character recognition (OCR) software,inserting the digitized visual content image into an electronicdocument, and transmitting the digitized visual content image over anetwork.

The operation of such scanners generates captured image data (alsoreferred to as image sensing data) and position indicating data (alsoreferred to as position sensor data). The captured image data representsan image of visual content of a scanned object (e.g., a physicaldocument) physical document that is captured by an image sensor of thescanner. The position indicating data corresponds to a relative positionof the scanner when a corresponding portion of the captured image datacaptured. Combined, the captured image data and the position indicatingdata allow a complete digitized visual content image to be constructed.Scanners generally require a close tolerance between the captured imagedata and the position indicating data to accurately construct thedigitized visual content image. The more accurate the position andsensor data, the better the image produced by the scanner. Likewise,without accurate position indicating data, the image can be blurred orsmeared. However, because conventional scanners generally use mechanicalsystems to accurately secure and/or position physical documents relativeto the position sensor and/or image sensor, their ability to maintainclose tolerance between the sensor data and the position indicatingdata, thus adversely impacting image quality.

Various implementations of handheld scanners have been attempted. But,they have not been commercially or functionally successful. Inoperation, these conventional handheld scanners take a series of imagesas a user moves the scanner across a physical document. The series ofimages are then assembled into the final image based on positionindicating data of each capture image.

A key drawback with most conventional handheld scanners is that thescanned image is of poor quality. There are many factors that,cumulatively, can cause poor image quality, of which a few are describedhere. One problem with most conventional handheld scanners is that theuser has no way of knowing if they have completely scanned an entirearea of the scanned object until the final image is viewed. If the userhas not scanned a portion of the scanned object during the scanningprocess, the user must rescan the scanned object again with nore-assurance that they will not inadvertently scan a different portionof the scanned image, thus resulting in a poor user experience. Anotherproblem with most conventional handheld scanners is that the positionindicating data typically becomes more inaccurate as the errors in theposition indicating data accumulate with the number of scanned tiles,thus resulting in an inaccurate image with blurring and other errors.Other errors in the scanned image can come from scratches in the cameralens, poor assembly of the individual tiles, and/or low image processingspeed, which can all result in poor quality scanned images and/or a pooruser experience.

SUMMARY OF THE DISCLOSURE

The present invention comprises a handheld scanner system and method. Ahandheld scanner system configured in accordance with the presentinvention operates to digitize an area of a scannable object (e.g., adocument). The handheld scanner system can comprise a scanner and ascanner software application. The scanner can include a body having anupper surface and a lower surface, a positioning system and an imagingsystem. The imaging system can include a lighting subsystem and an imagesensor subsystem.

The imaging system operates to digitize areas of the scannable object asthe scanner is moved across the scannable object. In particular, thelighting subsystem illuminate at least a portion of the scannable objectand the image sensor subsystem digitizes at least a portion of thescannable object illuminated by the lighting subsystem. The image sensorsystem then computes and outputs captured image data.

The positioning system operates to detect the relative position and/ormovement of the scanner as it moves across the scannable object. Thepositioning system outputs the position indicating data corresponding toa position and orientation of the handheld scanner with respect to theimage being scanned. The position indicating data is correlated with thecaptured image data.

The scanner software application receives the position indicating dataand captured image data and constructs a feedback image and outputimage. The feedback image enables a user to view the areas of thescannable object that have been digitized and can also highlight theareas of the scannable object that have not been digitized. The resultof the scanning process is an output image having higher quality andresolution than conventional handheld scanners.

Certain embodiments can have all, some or none of the followingadvantages. One advantage of at least one embodiment is that thenegative effects of defects in the images are reduced. Another advantageof at least one embodiment is that image detail is increased. A furtheradvantage is that the images are more aesthetically pleasing.

In one embodiment of the present invention, a scanner comprises aposition indicating system, an imaging system, and a data processingarrangement. The position indicating system is configured for generatingposition indicating data instances. The position indicating datainstances each includes data derived from translational movement of thescanner within a reference plane and from rotational movement of thescanner about a rotational axis extending through the reference plane.The imaging system is configured for capturing an image of visualcontent of a scannable object on which the scanner is being moved. Thedata processing arrangement is configured for deriving from at least oneof the position indicating data instances a position of the scanner at apoint in time when the image capturing was one of initiated, completed,and partially completed.

In another embodiment of the present invention, a scanner comprises ahousing having a first surface configured for being engaged by a hand ofa user and a second surface configured for slideably supporting thehousing on a surface of a scannable object. The scanner furthercomprises means coupled to the housing for sensing translationalmovement of the housing, means coupled to the housing for sensingrotational movement of the housing, and means coupled to the housing forcapturing an image of visual content on the surface of the scannableobject.

In another embodiment of the present invention, a scanner systemcomprises at least one processor, memory coupled to the at leastprocessor, and instructions accessible from the memory by the at leastone processor. The instructions are configured for causing the at leastone processor to generate a plurality of position indicating datainstances along a first timeline interval. The position indicating datainstances each corresponds to a position of a scanner at a respectiveposition along a path of movement of the scanner. The instructions areconfigured for causing the at least one processor to generate a capturedimage data instance along a second timeline interval longer than thefirst timeline interval. The captured image data is captured from visualcontent on a surface on which the scanner is supported and moved. Theinstructions are configured for causing the at least one processor touse at least two of the position indicating data instances forinterpolating a position of the scanner when generation of the capturedimage data instance was one of initiated, completed, and partiallycompleted.

In another embodiment of the present invention, a computer-readablemedium has computer-executable instructions accessible therefrom. Thecomputer-executable instructions are configured for controlling at leastprocessor to perform a method of processing sensor data generated by animage scanner. The method can comprise the operations of receivingposition indicating data instances each one of the position indicatingdata instances includes data derived from translational movement of thescanner within a reference plane and from rotational movement of thescanner about a rotational axis extending through the reference plane,receiving an image of visual content of a scannable object on which thescanner is being moved, and deriving from at least a portion of theposition indicating data instances a position of the scanner at a pointin time when the image capturing was one of initiated, completed, andpartially completed.

In another embodiment of the preset invention, a scanner system operableto be used by a user to digitize an area of a scannable object comprisesa handheld scanner and a software application. The handheld scannercomprises a positioning system and an imaging system. The positioningsystem is configured for detecting a planar position of the handheldscanner and a rotational orientation of the scanner at the planarposition and for outputting a plurality of position indicating datainstances derived from the planar position of the handheld scanner andthe rotational orientation of the handheld scanner. The imaging systemis configured for illuminating a portion of the scannable object and fordigitizing at least a portion of the scannable object illuminatedthereby to generate a plurality captured image data instances. Thesoftware application is configured for receiving, from the handheldscanner, the position indicating data instances and the captured imagedata instances, for constructing a feedback image using the positionindicating data instances and the captured image data instances, and forconstructing an output image using the position indicating datainstances and the captured image data instances. The feedback image isconstructed in a real-time manner or near real-time manner as the usermoves the handheld scanner across the scannable object. The output imagehas a resolution at least equal to a resolution of the feedback image.

Other technical advantages will be readily apparent to one skilled inthe art from the following figures, descriptions, and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the embodiments of the presentinvention and the advantages thereof, reference is now made to thefollowing description taken in conjunction with the accompanyingdrawings, wherein like reference numerals represent like parts, inwhich:

FIG. 1 is a schematic view of a handheld scanner system in accordancewith an embodiment of the present invention;

FIG. 2 is perspective view of a handheld scanner and tablet inaccordance with an embodiment of the present invention;

FIG. 3 is a bottom perspective view of a handheld scanner in accordancewith the present invention;

FIG. 4 is fragmentary view showing the interior space of the handheldscanner shown in FIG. 3 and showing spatial relationship of image systemcomponents within such interior space;

FIG. 5 is a schematic view of the handheld scanner of FIG. 3;

FIG. 6 is a diagrammatic view showing a scan path along visual contentof a scannable object to be scanned using a scanner system configured inaccordance with the present invention;

FIG. 7 is a diagrammatic view showing tiles generated over the scan pathof the scannable object shown in FIG. 6;

FIG. 8 is a diagrammatic view showing a feedback image in accordancewith the present invention, which shows the tile generated along thescan path of the scannable object shown in FIG. 6;

FIG. 9 is a diagrammatic view showing a chronological relationshipbetween position indicating data and captured image data in accordancewith an embodiment of the present invention;

FIGS. 10A and 10B are flow diagrams showing a method for performingimage processing functionality in accordance with an embodiment of thepresent invention;

FIG. 11 is a flow diagram showing a method for creating an abstract tileimage in accordance with an embodiment of the present invention;

FIG. 12A is an illustrative view of a scanned image in accordance withan embodiment of the present invention;

FIG. 12B is a graph of a distribution curve corresponding tocorrelatable features of the scanned image of FIG. 12A;

FIG. 13A is an illustrative view of an abstract tile image derived fromthe scanned image of FIG. 12 A;

FIG. 13B is a graph of a distribution curve corresponding tocorrelatable features of the abstract tile image of FIG. 13A;

FIG. 14 is an illustrative view of an angularly offset differentialabstract tile image derived from the abstract tile image of FIG. 13A;

FIG. 15 is a flow diagram showing a method for re-tensioning tiles inaccordance with an embodiment of the present invention; and

FIG. 16 is a flow diagram showing a method for creating a feedback imagein accordance with an embodiment of the present invention.

DETAILED DESCRIPTION OF THE DRAWING FIGURES

FIGS. 1 through 16 illustrate various aspects of a handheld scannersystem and method configured in accordance with an embodiment of thepresent invention. The present invention is illustrated in terms of acomputer mouse having a scanner integral therewith. It should beunderstood that the present invention can comprise other embodimentswithout departing from the spirit and scope of this invention. Forexample, the present invention can be incorporated into a standalonehand scanner or other suitable type of scanner systems.

FIG. 1 is a schematic view of a handheld scanner system 10 in accordancewith an embodiment of the present invention. In the depicted embodiment,the handheld scanner system 10 comprises a scanner 12 and a scannersoftware application 14. Preferably, but not necessarily, the scanner 12is a manually-movable (e.g., handheld) scanner.

Referring now to FIGS. 1 and 2, the scanner 12 operates to digitizevisual content of a scannable object 16 and output position indicatingdata PID and captured image data CID to the scanner software application14. It is disclosed herein that sensor data configured in accordancewith the present invention can include the position indicating data PIDand the captured image data. Examples of the scannable object 16include, but are not limited to, a textual document, a photograph, amap, an illustration, a 3-dimensional object having scannable indiciaprovided thereon, and other structures having visual content providedthereon. The position indicating data PID includes translationalposition indicating data within an X-Y plane and includes rotationalposition indicating data of the scanner 12 about a Z-axis, as shown inFIG. 2. Thus, the term position indicating data as used herein refers totranslational and rotational information that defines movement of ascanner. The captured image data CID includes data comprising an imagecaptured by the scanner 12.

Preferably, the position indicating data PID and the captured image dataCID each include respective information allowing a given portion of thecaptured image data CID to be synchronized with (e.g., correlated to) acorresponding portion of the position indicating data for the purpose ofcorrelating relative position of discrete digitized images generated bythe scanner 12. For example, in one embodiment of the present invention,the captured image data CID of a sensor data instance includes aplurality of discrete digitized image of the scannable object 16 and theposition indicating data PID includes a plurality of discrete scannerposition (e.g., x-y-z axes coordinates) correspond to a position of thescanner when the captured image data is generated. As will be describedbelow in greater detail, processing a digitized image by the scannersoftware application 14 can include correlating a relative position ofthe digitized image with other corresponding digitized images. To thisend, time stamping of position indicating data PID and time stamping ofcaptured image data is one embodiment of the position indicating dataPID and the captured image data CID each including respectiveinformation allowing the captured image data CID to be synchronized with(e.g., correlated to) corresponding position indicating data for thepurpose of correlating relative position of digitized images generatedby the scanner 12.

The scanner software application 14 operates to receive the positionindicating data PID and the captured image data CID from the scanner 12and construct a feedback image 22 and an output image 24. The feedbackimage 22 is displayed on visual display 26 and allows the user to viewthe movement of the scanner 12 across the scannable object 16 anddetermine which areas of the scannable object 16 have been scanned andwhich areas of the scannable object 16 have not been scanned. The outputimage 24 can be displayed, printed, stored or electronicallycommunicated.

The configuration of the handheld scanner system 10 often depends on thetype of scannable object 16 to be digitized. In the depicted embodiment,the handheld scanner system 10 is a mouse scanner system, wherein thescanner 12 is implemented as a computer mouse scanner and the scannersoftware application 14 operates on a computer 30. A keyboard 27 can becoupled to the computer 30 for manually entering information usingkeystrokes. In another embodiment, the handheld scanner system 10comprises a standalone unit where the scanner 12, the scanner softwareapplication 14, and the display 26 are integrated together into a singleportable device.

As shown in FIGS. 1 and 2, the handheld scanner system 10 can alsoincludes a tablet 28. The tablet 28 can operate in conjunction with thescanner 12 to determine the position of the scanner 12. Accordingly, itis disclosed herein that the position indicating data PID can be outputby the scanner 12, the tablet 28, or both the scanner 12 and the tablet28.

The scanner software application 14 can comprise any suitable computerreadable instructions operable to receive the position indicating dataPID and captured image data CID and to construct the feedback image 22and output image 24. The feedback image 22 preferably includes a panarea (e.g., viewable area) that automatically changes its displayedboundaries based on the position of the scanner 12. The displayedboundaries to be scanned are generally defined by the maximum andminimum positions of the scanner 12 with the X-Y plane. The feedbackimage 22 also preferably includes visual indicators 34 that show theareas of the scannable object 16 within the boundaries that have notbeen scanned by scanner 12. For example, the visual indicators 34 areshown in relative position to portions of the visual content of thescannable object 16 that has already been scanned. As unscanned portionsof the visual content of the scannable object 16 are scanned, the visualindicators 34 are replaced by the representation of the scanned visualcontent of the scannable object 16.

The visual indicators 34 can include color highlights and variations inintensity to call the users attention to potential areas that need to bescanned. In one embodiment, the visual indicators 34 can include apattern of colors, pattern of shapes, particular color or other highlyrecognizable indicator to highlight areas that have not been digitized.The visual indicators 34 can also comprise high intensity colors, likered, that highlight areas that have not been scanned by scanner 12.Furthermore, the visual indicators 34 can include drop shadows. It isdisclosed herein that the present invention is not unnecessarily limitedto any particular configuration of such visual indicators.

The scanner software application 14 can also include tools 36 (e.g., viaa graphical user interface) for modifying the feedback image 22 andoutput image 24. The tools 36 will generally include color/contrastediting, image resize, image rotation, storing and image clearingfunctions, to name a few. The tools 36 will also preferably includesettings that allow the user to select the type of visual indicators 34to be used on the feedback image 22. It is disclosed herein that thescanner software application 14 can include other suitable functions andprocesses.

The visual display 26 can comprise any suitable device operable todisplay the feedback image 22 to the user. In the depicted embodiment,as illustrated, the visual display 26 is a computer monitor. In otherembodiments, such as used in a standalone unit, the visual display 26can comprise a liquid crystal display or such other suitable displaytechnology.

The computer 30 includes a processor 31, memory 33 and a communicationinterface 35. Instructions 37 within the memory 33 are accessible by theprocessor 31 for allowing the processor 31 to carry out functionality ofthe computer 30. One example of such computer functionality is runningthe scanner software application 14. The scanner software application 14can reside within the memory 33 or within a different storage device ofthe computer 30 and/or accessible by the processor 31. In oneembodiment, the scanner 12, the visual display 6, the keyboard 27 andthe tablet 28 are coupled to the computer via the communicationinterface 31. A Universal Serial Bus (USB) port and or a USB hub areexamples of the communication interface 31.

Referring now to FIGS. 3-5, the scanner 12 is shown configured inaccordance with a preferred embodiment of the present invention. In thisembodiment, the scanner 12 comprises a body 40 having an upper surface42, a lower surface 44 and edge faces 45. As denoted in FIG. 5, thescanner 12 includes a positioning system 46 configured for outputtingposition indicating data PID and an imaging system 48 configured foroutputting the captured image data CID.

Still referring to FIGS. 3-5, the body 40 can have any suitable size orshape that enables the user to hold the scanner 12 in their hand andscan a scannable object (e.g., the scannable object 16). The body 40 canalso include low-friction members 50 (or a one-piece shield) mounted onthe lower surface 44 and that are configured to enhance sliding of thebody 40 across the scannable object 16 with uniform movement. Thus, thelower surface 44 is one embodiment of a support surface of the scanner12. Although not specifically shown, the body 40 can also include a skinor other suitable structure that covers a portion of the lower surface44 for helping to protect components of the position indicating system46 and/or the imaging system 48 from damage, contamination, and thelike.

In the depicted embodiment, the scanner 12 includes a communicationinterface 47 that provides for allowing communication of the positionindicating data PID and the captured image data CID to the scannersoftware application 14 operating on the computer 30. To this end, thecommunication interface 47 is coupled (e.g., in a wired or wirelessmanner) to the communication interface 35 of the computer 30.Preferably, the communication interface 35 of the computer 30 and thecommunication interface 47 of the scanner 12 jointly provide forsufficient bandwidth to allowing transmission of the position indicatingdata PID and captured image data CID data from the scanner 12 to thecomputer 30 at a real-time or near real-time data rate.

The positioning system 46 can comprise any suitable device or system fordetermining the relative position of the scanner 12 with respect to ascannable object being scanned. In the depicted embodiment, thepositioning system 46 includes a plurality of speed indicating sensors54 that enable relative movement of the scanner 12 within the X-Y plane(shown in FIG. 2) to be determined. The speed indicating sensors 54 arefurther configured (e.g., physically positioned) in a manner forallowing relative motion of the scanner 12 around the Z-axis (shown inFIG. 1) to be determined. As such, interferometers (i.e., opticalsensors) are examples of the speed indicating sensors. The speedindicating sensors 54 are preferably located near the edges 45 on thelower surface 44 of the body 40. Locating the speed indicating sensors54 near one or more edges 45 helps detect when a portion of the imagingsystem 48 moves beyond the scannable object 16.

The positioning system 46 can also include at least one accelerationindicating sensor 56 configured for enabling a rate of change in speedof the scanner 12 during movement thereof to be determined, at least onerotation indicating sensor 57 configured for enabling a rotationalorientation of the scanner 12 to be determined, or both. The inclusionof the acceleration indicating sensor 56 and/or the rotation indicatingsensor 57 can increase the accuracy and/or degree of resolution of theposition indicating data. A sensor that senses acceleration and/orchange in acceleration (e.g., an accelerometer) is referred to herein asan acceleration indicating sensor. A gyroscopic sensor is an example ofa rotation indicating sensor that is capable of sensing rotation of thescanner 12. Thus, position indicating data in accordance with thepresent invention can include discrete data from each sensor of apositioning system, composite position indicating data derived from atleast a portion of the sensors, or both. For example, in one embodiment,position indicating data includes discrete data from a plurality ofinterferometers.

The scanner 12 is preferably further configured to detect when thescanner 12 is lifted from the scannable object 16 or when all or aportion of the optical sensors 54 are off the scannable object 16.Although the positioning system 46 is described in terms ofaforementioned sensors, the positioning system can comprise othersuitable sensors without departing from the scope and spirit of thepresent invention. It is disclosed herein that the scanner can includeonly speed indicating sensors 54 when the speed indicating sensors 54are suitably configured for providing the position indication data PID.For example, when the optical sensors 54 are interferometer sensorshaving suitable operating characteristics (e.g., each including anintegrated lighting source and velocity sensor) and performance, suchinterferometers can suitably provide the position indicating data PID.Preferably, the sensor or sensors of the position indicating systemprovide a suitable degree of accuracy in the position indicating dataover a suitable range of speeds over which the scanner 12 is typicallymoved.

The imaging system 48 can comprise any suitable device or system fordigitizing an area of a scannable object having visual content thereon(e.g., the scannable object 16 shown in FIG. 2). In the depictedembodiment, the imaging system 48 comprises a lighting subsystem 60 andan image sensor subsystem 62. The lighting subsystem 60 operates toilluminate an area of a scannable object to be scanned and the imagesensor subsystem 62 operates to digitize an area of the scannable objectilluminated by the lighting subsystem 60 during illumination thereof bythe lighting subsystem 60.

The lighting subsystem 60 can comprise any suitable illumination device.In the depicted embodiment, the lighting subsystem 60 comprises one ormore light emitting diodes (LED) units 64 and, optionally, one or morelight reflecting devices 65 (e.g., a mirror) associated with each one ofthe LED units 64. The LED units 64 and light reflective devices 65 arearranged and configured to project and/or reflect light through a coverglass 66, which can be a glass or polymeric material, and that ismounted within or over an opening 67 within the lower surface 44 of thebody 40. In this manner, light from the lighting subsystem 60 canilluminate the portion of the scannable object to be scanned that isexposed within the opening 67. It is disclosed herein that a skilledperson will appreciate that the lighting subsystem 60 can also includeone or more other devices for enhancing the quality and intensity oflight delivered from the lighting subsystem 60 to the scannable objectbeing scanned. Examples of such other devices include, but are notlimited to, a lens, a filter, or the like.

The LED units 64 are examples of suitable light sources configured forilluminating a scannable object being scanned. Optimally, the LED units64 produce light (not limited to but including red, green, blue, andother colors of light), or such other suitable combination of light toproduce red, green and blue captured image data CID. In one embodiment,the lighting subsystem 60 comprises a bar of white (or red, green andblue) LEDs 64. In another embodiment, the lighting subsystem 60comprises multiple bars of LED units 64.

The operation of the lighting subsystem 60 can also be optimized throughthe manner in which the LED's 64 are configured and/or operated. In oneembodiment, the LEDs 64 flash each one of a plurality of colors (e.g.,red, green, and blue) in series so that the image sensor subsystem 62detects colors associated with each color of LED 64. In anotherembodiment, the image sensor subsystem 62 includes separate colordetection sensors and the LEDs 64 flash all at once. In at least oneembodiment, the lighting subsystem 60 can also comprise a white lightillumination system.

The image sensor subsystem 62 can comprise any suitable image capturesystem. In the depicted embodiment, the image sensor subsystem 62includes an image capturing sensor 68, a sensor lens 69 and a field lens70. The field lens 70 is mounted on or adjacent to the cover glass 66.The image capturing sensor 68 is mounted at a distance above the fieldlens 70 with the sensor lens 69 located at a position between the imagecapturing sensor 68 and the field lens 70. Jointly, the configurationand relative positioning of the image capturing sensor 68, the sensorlens 69, and the field lens 70 cause light, which is being reflectedfrom the scannable object being scanned through the cover glass 66, tobe impinged onto a light receiving surface of the image capturing sensor68. In this manner, the field of view of the image capturing sensor 68can be approximately or entirely an area of the opening 67. While theimage sensor subsystem 62 is shown as including only one image capturingsensor 68, it is disclosed herein that the image sensor subsystem 62 caninclude a plurality of sensors 68, thereby enhancing resolution ofscanned visual content of a scannable object. In one embodiment, a lensarrangement in accordance with the preset invention includes the sensorlens 69 and the field lens 69.

It is disclosed herein that a skilled person will appreciate that theimage sensor subsystem 62 can also include one or more other devices forenhancing the quality and intensity of light reflected from thescannable object being scanned to the image sensor subsystem 62.Examples of such other devices include, but are not limited to, a lens,a filter, or the like. Furthermore, in a preferred embodiment, at leastone lens of the image sensor subsystem 62 is a telecentric lens, apolarized lens or a combination thereof.

In the depicted embodiment, the image capturing sensor 68 comprises anarea array sensor that digitizes a small area of the scannable objectbeing scanned. The resulting captured image data for a given sensor datainstance is referred to herein as a tile. Each tile includes a digitizedimage of a respective portion of the scanned scannable object. Thus, theimage sensor subsystem 62 functions as a digital camera that producesdigitized segments (e.g., tiles) of an image being scanned. In anotherembodiment, the image capturing sensor 68 comprises a line array sensorthat operates to digitize a line as the scanner 12 passes over thescannable object 16.

Preferably, the lighting subsystem 60, the image sensor subsystem 62,the opening 67, and the cover glass 66 are jointly configured forallowing the image sensor subsystem 62 to digitize an area of ascannable object at or near at least one edge 45 of the body 40. Suchedge scanning functionality enables a complete page of a book, magazineand other such bound print materials to be scanned.

The scanner 12 preferably includes a processor 74 operable to receivethe position indicating data PID and captured image data CID from theposition indicating system 46 and the imaging system 48, respectively,pre-process such data, and then causes it to be transmitted to thescanner software application 14 running on the computer 30. To enablesuch transmission, it can be necessary to compress the data to minimizethe bandwidth required for communicating the data to the scannersoftware application 14.

The scanner 12 can further include memory 76. Instructions 78, whichdetermine operation of the communication interface 47, positionindication system 46, and/or the imaging system 48, can be stored on thememory 76 and can be accessible therefrom by the processor 74. It isdisclosed herein that the memory 76 can reside within the processor 74or be configured in a standalone manner with respect to the processor74. In at least one embodiment, the processor 74 can include memoryhaving the instructions 78 to be stored thereon and/or, if the bandwidthis insufficient to communicate the data in real-time to the scannersoftware application 14, having position indicating data PID and/orcaptured image data CID buffered thereon. In one embodiment, theinstructions 78, processor 74, and the memory 76 jointly define firmwareof the scanner 12. However, it is disclosed herein that sensor data inaccordance with the present invention can be generated and/or processedby any suitable data processing arrangement (e.g., including firmware,software, processors, memory, etc).

Functionality provided by the communication interface 47 includesenabling communication between the scanner 12 and the computer 30 (e.g.,communicating position indicating data and captured image data from thescanner 12 to the computer 30). One key aspect of such communicationinterface functionality is that position indicating data and capturedimage data is preferably transmitted for reception by image processingsoftware (e.g., scanner software application 14 discussed above inreference to FIG. 1) at a real-time or near real-time data rate withrespect to generation of such data. Functionality of the positionindicating system 46 includes generating position indicating data andfunctionality of the imaging system includes generating captured imagedata. The instructions 78 can be configured for providing all or aportion of such functionalities. In one embodiment, the sensor dataconfigured in accordance with the present invention includes positionindicating data, captured image data, time stamp information indicatingwhen the position indicating data was generated, and time stampinformation indicating when the captured image data was generated.

In view of the foregoing discussion, a skilled person will appreciatethat the scanner 12 (e.g., through firmware thereof) is configured forproviding sensor data capture functionality. In one embodiment, suchsensor data capture functionality can be provided for by firmware of thescanner. More specifically, the firmware can provide for such imagecapture functionality through joint control of the imaging system 48 andthe position indicating system 48. To this end, in operation of thescanner, the firmware performs an operation for sending out a trigger(e.g., a signal) for causing the LED(s) 64 of the lighting subsystem 60to illuminate visual content of a scannable object upon which thescanner 12 is resting and correspondingly performs an operation forsending out a trigger for causing the position indicating system 46 tobegin collecting position indicating data (e.g., scanner velocityinformation). Preferably, the triggers are outputted at a constant ratewith respect to each other. In response to illumination of the LEDs, thefirmware causes the image sensor(s) 68 of the image sensor subsystem 62to start a time period where the image sensor(s) 68 collect photonsemitted from the LED(s) 64 and reflected from the surface of thescannable object. At the end of the time period, captured image datafrom the image sensor(s) 68 is transferred to a first buffer internal tothe scanner 12 (e.g., part of the memory 76 or a discrete first bufferdevice not shown). Associated position indicating data (e.g.,interpolated position indicating data discussed below) from the positionindicating system 46 along with other information associated with theposition indicating data (e.g., time stamp information, scanner buttonstate(s), lift bit indicating that a position indicating sensor is toofar from the surface, etc) can be stored with the captured image data.While the first buffer is being updated with the current sensor data,sensor data within a second buffer internal to the scanner (e.g., partof the memory 76 or a discrete first buffer device not shown) is beingtransferred to an apparatus that provides image processing functionality(e.g., the computer 30). In one embodiment, sensor data is transferredfrom the first buffer to the second buffer in response to such sensordata of the first buffer being processed to a form required forperforming image processing functionality in accordance with the presentinvention). However, other suitably configured data processingarrangements can be implemented for providing such sensor data capturefunctionality

It is disclosed herein that the scanner 12 is configured in a mannerallowing it to provide scanner functionality in accordance with thepresent invention and to also provide user input device functionality ofa device commonly referred to as “a mouse”. In one embodiment, theposition indicating data PID generated by sensors of the positionindicating system 46 is used for providing such mousing functionality.

Referring now to FIGS. 6-8, a relationship between position indicatingdata and captured image data is shown. As shown in FIG. 6, a scannableobject (e.g., a document) has visual content 119 provided therein in theform of three lines of alphanumeric characters. A scan path 121identifies a path over which a scanner configured in accordance with anembodiment of the present invention (e.g., the handheld scanner 12)traverses during scanning of the scannable object 116. FIG. 7 showstiles 123 resulting from such scanning along the scan path 121. Each oneof the tiles 123 represents an area imaged by the scanner at arespective point in time and, thus, includes a portion of the visualcontent 119 of the scannable object 119. Each one of the tiles 123 has asubstantially common width W and height H corresponding to a discreteimaged area produced by the scanner. While each one of the tiles 123 isshown as being rectangular in shape, it is disclosed herein that eachone of the tiles 123 can be a shape different than rectangular (e.g.,round).

Each one of the tiles 123 has respective position indicating data andcaptured image data associated therewith. The position indicating dataincludes information designating a position of a particular one of thetiles 123 within an X-Y plane of the scannable object at the point intime when a respective one of the tiles 123 was created and includesinformation designating rotation about a Z-axis at the point in timewhen the respective one of the tiles 123 was created. The Z-axis extendsperpendicular to the X-Y plane. In one embodiment, the positionindicating data for each one of the tiles 123 includes a relativeposition of a particular one of the tiles 123 with respect to a locationof a first one of the tiles 123. In another embodiment, the positionindicating data for each one of the tiles 123 includes a relativeposition of a particular one of the tiles with respect to an immediatelyprior one of the tiles 123 (i.e., the image tile generated immediatelyprior to the particular one of the tiles). As such, each one of thetiles 123 can subsequently be positioned with respect to immediatelyadjacent ones of the tiles 123 to reconstruct the visual content 119scanned from the scannable object 116.

The area of each tile 123 is approximately the same as a scan area ofthe scanner that creates each one of the tiles 123. Furthermore, as canbe seen, the scan area of a scanner configured in accordance with thepresent invention is a fraction of the overall area of visual content ofa scannable object being scanned with the scanner. As such, to captureall desired visual content of a scannable object, a scanner configuredin accordance with the present invention requires that the scanner bemoved about the scannable object until all of the desired visual contenthas been scanned. To assist a user in ensuring that all desired visualcontent has been scanned during a scanning session, embodiments of thepresent invention can include displaying a feedback image that depictsareas of a scannable object that have been scanned and those that havenot.

FIG. 8 shows a feedback image 127 resulting from partial or incompletescanning of the scannable object 116 during a scan session (i.e., asingle contiguous scan path). As can be seen, the feedback image 127shows portions of the visual content 119 that has been scanned (i.e.,scanned area 128) and includes a visual indication 129 of unscannedportions of the visual content 119 (e.g., a shaded area or otherwiseidentifiable manner of denoting an unscanned area). In this manner,unscanned portions of the scannable object 116 that are unintentionallynot yet scanned, but which are intended to be scanned, can be scannedduring the scan session, thereby allowing a single scan process tocapture all intended portions of the visual content 119. The visualindicator 129 allows unscanned areas of visual content 131 to be readilyidentified. During a scan session, reconstruction of the visual content119 from the tiles 123 can be provided in a real-time or near real-timemanner (e.g., based upon relatively low-resolution processing of thecaptured image data) for creating the feedback image 127 that shows theportions of the visual content 119 that has been scanned. It isdisclosed herein that scanning over an already scanned portion of thevisual content 119 during a scan session does not adversely impact suchscanning or re-construction of the scanned image because unneededcaptured image data from tiles can be omitted and/or deleted whencreating a feedback image and/or output image.

Creating an image using position indicating data and captured image datain accordance with the present invention requires correlating each tile123 (i.e., a discrete portions of captured image data) with acorresponding portion of the position indicating data. In doing so, aposition in which the scanner captured a particular one of the tiles 123can be determined. Knowing relative positions of the tiles enables theimage to be created by stitching the tiles together in properorientation and order. A feedback image (i.e., relatively lowresolution) is one example of an image created using position indicatingdata and captured image data in accordance with the present invention.An output image (i.e., relatively high resolution) is another example ofan image created using position indicating data and captured image datain accordance with the present invention.

Referring now to FIG. 9, relationship between position indicating dataand captured image data is discussed in detail. As a scanner (e.g.,scanner 12) is displaced along a displacement path (i.e., scannerdisplacement path SDP), the scanner generates position indicating dataPID and captured image data CID at a plurality of scanner positions SPalong the scanner displacement path SDP. The position indicating dataPID is generated at a first frequency along a position indicating datatimeline TPID and the captured image data CID is generated at a secondfrequency along a captured image data timeline TCID. In the depictedembodiment, the first frequency is greater than the second frequency,thus resulting in a greater amount of discrete position indicating datainstances than discrete captured image data instances (i.e., tiles). Itis disclosed herein that, in other embodiments, the first frequency andthe second frequency can be substantially the same.

Each one of the hash lines on the position indicating data timeline TPIDindicates a time at which generation of position indicating data PID isinitiated for a corresponding position of the scanner 12 (i.e., discreteposition indicating data instance) and each one of the hash lines on thecaptured image data timeline TCID indicates a time at which generationof captured image data CID is initiated for a corresponding position ofthe scanner 12 (i.e., discrete captured image data instance). Thus,position indicating data represents a relative position of the scannerwhen such position indicating data is initiated or generated andcaptured image data that represents an imaged area of visual content ofa scanned object (i.e., a tile) when capture of an image correspondingto captured image data is initiated or generated by the scanner.

It is disclosed herein that, each data instance (i.e., positionindicating data or captured image data) can include creation timeinformation (e.g., a timestamp) that indicates relative time at whichcreation of the data instance was initiated. It is preferred for eachone of the captured image data instance to be chronologically alignedwith a respective position indicating data instance. In this manner, anexact position of the scanner when an image corresponding to aparticular captured image data instance would be known or determinable.To this end, it is advantageous for discrete position indicating datainstances and discrete captured image data instances to be transmittedfor reception by image creation software (e.g., scanner softwareapplication 14 discussed above in reference to FIG. 1) at a real-time ornear real-time data rate with respect to generation of such datainstances.

However, in practice, a time at which a discrete captured image datainstance is initiated will generally not be chronologically aligned witha time at which any one of the discrete position indication datainstances is initiated. For example, as shown in FIG. 9, a time at whicha captured image data instance is initiated at a particular scannerposition SP is between two adjacent position indicating data instances.One reason for such asynchronous timing between the position indicatingdata PID and the captured image data CID is that the position indicatingdata PID can be generated at a higher frequency than the captured imagedata CID. Another reason is that, even if the data generation rates forthe position indicating data PID and the captured image data CID was thesame, maintaining data generation frequency for the position indicatingdata PID with a first timing device (e.g., a first clock) andmaintaining data generation frequency for the captured image data CIDwith a second timing device (e.g., a second clock) can result in anchronological (i.e., timeline) offset between data generation timing forthe position indicating data and captured image data. For example, asshown in FIG. 9, unless both clocks are started simultaneously, clocksrunning at the same clock rate or multiples thereof will be misalignedthereby creating a clock initialization offset CIO that is constant overtime. As shown in FIG. 9, sensors that generate the position indicatingdata (e.g., a plurality of interferometers) operate at a frequency thatis an even multiple of the frequency at which a sensor that generatesthe captured image data CID operates. Accordingly the clockinitialization offset is constant.

In view of such asynchronous timing between position indicating data andcaptured image data, embodiments of the present invention can requirethat time-based computations be performed for accurately determining aposition of the scanner when each discrete captured image data instancein captured. Such determination is also referred to herein asinterpolation. The underlying objective of such computations is toapproximate a relatively precise location of the scanner at the time thescanner captured an image corresponding to a particular discretecaptured image data instance.

Referring now to FIGS. 10A and 10B, a method 200 for performing imageprocessing functionality in accordance with an embodiment of the presentinvention will be discussed. Such image processing functionality enablesoutput of one or more types of images derived from sensor data generatedand configured in accordance with the present invention (e.g., positionindicating data PID and the captured image data CID discussed above). Animage outputted by the image processing instructions is a reconstructionof a scanned image from which the position indicating data and capturedimage data was generated by a scanner in accordance with the presentinvention (e.g., the scanner 12 discussed above).

At an operation 202, the method 200 provides for receiving a sensor datainstance for a current point in time (i.e., a current sensor datainstance). As discussed above, sensor data includes data from one ormore sensors configured for providing position indicating data and datafrom one or more sensors configured for providing captured image data(e.g., a tile). It has been disclosed above that position indicatingdata in accordance with the present invention can include discrete datafrom each sensors of a positioning system, composite position indicatingdata derived from at least a portion of the sensors, or both. Examplesof such position indicating data include, but are not limited to,information defining a position of the scanner, information defining avelocity of the scanner, information defining an acceleration of thescanner, and the like. Preferably, but not necessarily, the positionindicating data of the sensor data instance can include discrete datafrom a plurality of interferometers.

After the sensor data instance is recorded, an operation 204 isperformed for normalizing the position indication comprised by thecurrent sensor data instance. The underlying objective of performingsuch normalizing is to adjust the position indicating data to compensatefor known errors and non-linearities, thereby providing a consistentoutput for a given amount of scanner displacement. For example,interferometers are known to report different position deltas for thesame distance if the unit is moving relatively fast versus movingrelatively slow. Thus, it is preferred to normalize position deltas ofinterferometers. In one embodiment, normalizing the current sensor datainstance includes apply coordinate correction and bias to positionindicating data of the sensor data.

An operation 206 is performed for determining if the normalized positionindicating data of the current sensor data instance is valid afternormalizing the position indicating data of the current sensor datainstance. Validity of position indicating data can be determined byassessing various different scenarios. In one scenario, if the lift bitindicates that sensor is too far from the surface, then the dataposition data from that sensor is not representative of the actualmovement of the unit and can be deemed to be invalid. In anotherscenario, if position sensors data indicates that there is no motion andthe other sensors indicate reasonable motion, then it can be assumedthat the sensor corresponding to such non-movement has malfunctionedand, thus, position indication data corresponding to such malfunctioningsensor can be deemed invalid. In still another scenario, if positionindicating data indicates that there is maximum constant velocity, thenit can be assumed that the sensor corresponding to such maximum constantvelocity is likely in a runaway condition and the data from such sensoris not usable and can, thus, be deemed invalid. In still anotherscenario, position indicating data from all position indicating datasensors is compared to each other and to the physical geometry (i.e.,mounted position) of the sensors. A degree of validity (i.e., aconfidence) of each sensor's output can be determined by thiscomparison.

In the case where the normalized position indicating data of the currentsensor data instance is determined to the invalid, the current iterationof the method 200 ends. In the case where the normalized positionindicating data of the current sensor data instance is determined to bevalid, the method 200 continues at an operation 208 for determining aninterpolated position of the scanner at the point in time where capturedimage data of the sensor data is generated. The interpolated position isdefined by position indicating data corresponding to the point in timewhere captured image data of the sensor data is generated (i.e.,interpolated position indication data). Thus, creation time informationsuch as timestamps can be used for determining the interpolatedposition.

One reason such interpolation can be necessary is due to clockinitialization offset. As discussed above in reference to FIG. 9, clockinitialization offset occurs when separate clocks (e.g., those runningat the same frequency or multiples of each other) are used for timingthe generation of position indicating data instances and captured imagedata instances and such clocks are started in an offset manner such thattheir timing output indicators (e.g., ticks) are out of synchronizationwith each other. In general, generation of a captured image datainstance takes longer to generate than generation of a positionindicating data instance due to differential in time required forgenerating a captured image data instance with components of an imagingsystem of a scanner configured in accordance with the present inventionand time required for generating a position indicating data instancewith components of a position indicating system of a scanner configuredin accordance with the present invention. As such, a clock controllinggeneration of captured image data will generally run at a fraction ofthe speed of a clock controlling generation of position indicating data.As such, it is necessary to interpolate a position of the scanner when aparticular captured image data instance was generated.

Generation of a particular captured image data instance can correspondto the time at which generation of the particular captured image datainstance was initiated or can correspond to the time at which aspecified amount of such generation is completed (e.g., 50% of the imagecapture process time duration for a tile is elapsed). Accordingly,another reason that such interpolation can be necessary relates tospecification of a point in time of the image capture process where theposition of the scanner needs to be known (i.e., position indicatingdata instance corresponding to the point in time). For example, if it isdetermined that the most useful captured image is centered around 50% ofthe image capture process time duration for a tile being elapsed fromwhen such processing was initiated, it will be advantageous to determineinterpolated position indicating data corresponding to that elapse timefrom when the image capture process was initiated (e.g., when a clockcycle indicated that such image capture process should begin).

After the interpolated position indicating data is determined, anoperation 210 is performed for transmitting the processed sensor datainstance (i.e., captured image data and interpolated position indicatingdata) from the scanner (i.e., a first scanner system apparatus) forreception by a scanner software application (i.e., a second scannersystem apparatus), followed by the scanner software applicationperforming an operation 212 for receiving the processed sensor datainstance. The scanner software application 14 discussed above is oneexample of such a scanner software application. Thus, in the depictedembodiment, the scanner (e.g., sensor data processing instructionsthereof) and the scanner software application are jointly configured forproviding image processing functionality in accordance with the presentinvention. In other embodiments, it is disclosed herein that such imageprocessing functionality can be performed entirely by the scanner orentirely by the scanner software application. A skilled person willappreciate that, when the image processing functionality is performedentirely by the scanner or entirely by the scanner software application,the operations for normalizing the position indicating data and/or theoperation for determining the interpolated position indicating data canbe performed at different locations within a method for performing imageprocessing functionality in accordance with the present invention. Forexample, the interpolated position indication data can be generated by ascanner software application running on a computer to which the scannersends as-generated (e.g., unprocessed) position indicating data.

Thereafter, as shown in FIG. 10B, the sensor data instance is used incarrying out various operations. The interpolated position indicatingdata of the sensor data instance can be used by an operation 214 fordetermining a momentum effect of the scanner at a point in time when thesensor data instance was generated. The interpolated position indicatingdata of sensor data instance can be used by an operation 216 fortransforming such interpolated position indicating position data tocorresponding universal image space position data. The captured imagedata of the sensor data instance can be used by an operation 218 forcreating an abstract tile image.

By determining the momentum effect of the scanner at the time the sensordata image was created, the momentum effect and/or information derivedtherefrom can be used in predicting the next position of the scanner(e.g., the position at which the current sensor data instance wasgenerated) and/or verifying the position of the captured image data ofthe sensor data instance with respect to captured image data of othersensor data instances. Determining the momentum effect can includeextrapolating a momentum effect of the scanner from position indicatingdata (e.g., translational and rotational orientation) of previouslyprocessed sensor data instances and using such momentum effect to verifyand/or approximate position indicating data for the current sensor datainstance. In essence, momentum associated with movement of the scannerprovides an estimate of a position to where the unit could move. Thus,the momentum effect can be used to predicted location/orientation of thescanner based on its momentum (e.g., the peak of the probabilitydistribution of possible locations/orientations).

Determining the momentum effect can include weighting the momentumeffect based on a degree of confidence in the accuracy/relevance of thedetermined momentum effect. It is disclosed herein that a confidencefactor can be applied to a determined momentum effect value forestablishing a confidence weighted momentum effect. Examples ofparameters upon which a confidence factor in accordance with the presentinvention can be derived include, but are not limited to, the accuracyof measurements made by sensors generating the position indicating data,how reasonable the position indicating data appears, the relativephysical geometry of the various sensors, specifications of the device,upper/lower limits on what is considered to be valid position indicatingdata, a requirement that the position indicating data should notconflict with the physical relationship of the sensor locations or otherparameters.

Universal image space is a spatial area that represents a displayedrepresentation of a scanned object and/or a printed presentation of thescanned object. Universal image space can be defined from coordinates ofa first image tile of a scanned image. For example, such coordinates ofthe first image tile can be the center of the first image tile with thefirst image tile defining an non-rotated orientation with respect to X,Y, and Z axes thereof. Transforming the interpolated position indicatingdata to corresponding universal image space position data includesdetermining where in a spatial area that captured image datacorresponding to the interpolated position indicating data is positioned(e.g., translational position (X-Y axes) and rotational position(Z-axis)). Such determination is derived, at least in part, by creatinga combined position estimate based on the position indicating dataassociated with a plurality of position indicating data sensors. Forexample, in the case where position indicating data for a given tile isgenerated for each one of a plurality of interferometers, the positionindicating data from all of the interferometers is used in deriving acombined estimate of the position (translational and rotationalpositions) of the tile.

Furthermore, transforming the interpolated position indicating data caninclude correcting the interpolated position indicating data for sensordrift. Sensor drift refers to discrepancies between relative physicallocation of the position indicating data sensors (e.g., relativelocation with respect to each other) and a computed position of theposition indicating data sensors as derived using the interpolatedposition indication data of each one of the position indicating datasensors. The underlying intent of accounting for sensor drift is tominimize error between the physical sensor locations and positionindicating data provided by such sensors. Based on the physical geometryof the scanner sensor and the confidences of the position indicationdata (i.e., scanner-generated position measurements), positionindicating data of each respective sensor can be adjusted to a bestestimate derived in view of the sensor drift. The sensor drift can alsobe used for specifying a new baseline value or calibration of the sensorpositions during generation of a subsequent sensor data instance,thereby allow deviation of position indicating sensors from theirphysical geometry positions and computed positions to be determined.

Creating an abstract tile image entails creating an image derived fromcaptured image data for the current sensor data instance.Advantageously, the abstract tile image provides distinct features of animage to which other tiles can be aligned. For example, well-definededges that are accentuated by the elimination/reduction of lesspronounced features and high-frequency noise serve as preferred featuresof a scanned image upon which a particular tile (i.e., captured imagedata instance) can be aligned to an adjacent tile. Aligning a pluralityof abstract images within the universal image space results in thecreation of a composite abstract image.

In many ways the abstract image is similar to an illustrative renderingof a photograph. Just as an illustration distills essential elements ofa photograph, the abstract image is intended to distill the real imageinto a form that is possible for a scanner software applicationconfigured in a accordance with the present invention to cross correlateon. The abstract image is an expedient to make it easier computationallyand more precise to find relation between a tile image and one or moreprevious tile images. To this end, it is advantageous for an appearance(i.e., format) of the abstract image to be customized for enabling suchcross correlation. A software application configured in accordance withthe present invention uses a direct mathematical cross-correlation oftwo images and tests the offset hypothesis with a limited set of probeoffsets. If every possible offset of a tile image is tried (i.e.,evaluated for relative positioning/fit) during such cross correlation,this would provide for a complete cross-correlation of captured imagedata but at the expense of lengthy processing time. All pixels in theoverlapping region between the current tile and the previous tile ormerged tiles is usually used in the cross correlation. However, to beefficient a limited number of alignments are tried to determine the bestalignment. If the alignments tried are spaced by more than one pixelapart at the resolution used for cross correlation, the actual peaklocation indicating the best alignment is determined by a paraboliccurve fit. This sparse alignment tries are possible because the abstractimage was constructed to produce a smooth correlation surface correlate(i.e., statistically a high peak that falls off from the peak withuniformly sloping shoulders). It is efficient and advantageous to usesparse alignment tries for the cross correlation calculations.

The ideal profile of the cross-correlation image is attained with imagesthat consist of sharp step functions as sharp edges. Thus, it isdesirable to abstract a real image (i.e., a tile image) into an abstractimage that has sharp edges across boundaries, but without ragged noisebetween. This is in fact the characteristic of a median filtered image.A median filter removes short impulses that would give a ragged terrainto the cross-correlation image, but it preserves the sharpness of edgesthat give a sharp peak to the cross-correlation with smooth and uniformslopes on each side, making it easy to find the peak with a small numberof probe points. Furthermore, a median is a form of averaging whereextreme points do not count more than non-extreme points. The medianvalue is defined as that value here half the samples are larger and halfthe samples are smaller. It doesn't matter if a larger sample isslightly larger or millions of times larger, it casts a simple “larger”vote. In a two-dimensional image (e.g., a tile image), a median averageremoves small dots completely, but it does preserve the profile andsharpness of edges.

Still referring to FIG. 10B, in conjunction with an operation 220 beingperformed for accessing a current composite abstract image, an operation222 is performed for cross correlating the current sensor data instancewith previously processed sensor data instances. The underlying purposeof such cross correlation is to provide an accurate translational androtational position of a current tile relative to the translational androtational position of other image tiles of previously processed sensordata instances. Accordingly, cross correlation determines alignmentcorrection (translation and rotational correction) needed to align atile with one or more previous tiles. In one embodiment of such crosscorrelation, a current tile's interpolated position indicating dataand/or the corresponding combined position estimate is used forcorrelating the position of the tile with tiles corresponding topreviously processed sensor data instances. For example, the currenttile's position indicating data and/or combined position estimate isused to compare image data (e.g., raw captured image data and/orabstract tile image data abstract) of the current tile with image dataof previously processed sensor data instances. The cross correlation intranslation and rotational orientation with previous tiles provides anadditional measurement of a tile's actual position and orientation inrelationship to tiles of previously processed sensor data instances.

It is disclosed herein that position indicating data provided byposition indicating sensors and an abstract images can be used forperforming cross correlation in accordance with the present invention.In such an embodiment, the position indicating data is used forproviding a general reference location of an image tile. However,because position indicating data can offer less than required and/ordesired accuracy, captured image data can be used to accomplish a moreaccurate cross correlation alignment. In particular, after the positionindicating data is used for determining a relative position between twooverlapping image tiles, abstract images of the two image tiles can beused for aligning such two image tiles with a greater degree ofaccuracy. For example, common features of such abstract images (e.g.,edges of the abstract image) can be aligned. Preferably, the capturedimage data will have higher resolution of accuracy that data provided bythe position indicating sensors and, thus, the resulting alignment fromthe abstract images will offer a greater degree of accuracy that if suchalignment relied solely on the position indicating data.

Thereafter, an operation 224 is performed for estimating an optimizedposition in universal space for the tile corresponding to the capturedimage data of the current sensor data instance. The underlying objectiveof estimating the optimized position of the tile (e.g., itstranslational position and rotational position) in universal image spaceis to provide a best estimate of the current tile's translationalposition and rotational orientation in the universal image space. Tothis end, estimating an optimized position for a tile can includecombining image correlation results with transformed sensor data (e.g.,transformed position indicating data, abstract tile image, etc) todetermine the best estimate of tiles' position. Position indicating data(i.e., sensor measurements), absolute and/or weighted scanner effect,and/or cross correlation results are examples of position optimizationinformation that can be used for estimating an optimized tile position.Furthermore, confidence factors can be derived for and applied to all ofsome of the position optimization information.

An operation 226 is preformed for creating a new composite abstractimage after estimating the optimized position in universal image spacefor the tile. The new composite abstract image includes the tilecorresponding to the current sensor data instance. As disclosed above,the abstract tile image provides distinct features of an image to whichother tiles can be aligned. As such, creating the new composite abstractimage includes using such distinct features to aligning the tile of thecurrent sensor data instance to a plurality of other abstract imagesthat have already been aligned within the universal image space.

FIG. 11 shows an embodiment of a method 300 for creating an abstracttile image. As has been disclosed above, creating an abstract tile imageentails creating an image derived from captured image data for thecurrent sensor data instance. The abstract tile image provides distinctfeatures of a tile image to which distinct features of other tile imagescan be aligned. For example, well-defined edges that are accentuated bythe elimination/reduction of less pronounced features and high-frequencynoise serve as preferred features of a scanned visual content upon whicha particular tile (i.e., captured image data instance) can be aligned toan adjacent tile.

At an operation 302, the method 300 provides for receiving capturedimage data of a sensor data instance currently being processed (i.e.,the currently processed sensor data instance). The captured image datais embodied as a tile having a portion of scanned visual content of ascannable object provided thereon (i.e., a tile image). After receivingthe captured image data, an operation 304 is performed for enhancingedges of the tile image thereby creating an edge-enhanced abstract tileimage. Thereafter, an operation 306 is performed for saving theedge-enhanced abstract tile image.

In one embodiment, creating the edge-enhanced tile image can includesubjecting the captured image data and/or derivatives thereof to one ormore tile processing steps. One example of such a tile processing stepsincludes a step 308 for determining relevant high frequency informationby applying a median filter to a tile image (e.g., an unprocessed tileimage or an abstract tile image). The median filter can be configuredfor eliminating noise while preserving strong edges. Another example ofsuch a tile processing steps includes a step 310 for weighting specificportions of a tile image (e.g., an unprocessed tile image or an abstracttile image) based on correlation feature quality. In effect, a weightingfilter is applied to a tile image for identifying portions of the tileimage whose content will be preferentially enhanced and those that willbe preferentially diminished. Another example of such a tile processingsteps includes a step 312 for applying a bandpass filter to a tileimage. The bandpass filter can be configured to remove high frequencynoise and low frequency mottling. Low frequency mottling is known toadversely impact correlation functionality particularly in view ofshading affects near edge of a tile image. Still another example of sucha tile processing steps includes a step 314 for applying a sharpeningfilter to a tile image. The sharpening filter can be configured forenhancing definition of edge features. Still further, another example ofsuch a tile processing steps includes a step 316 for creating anangularly offset differential abstract tile image from an existingabstract tile image. The angularly offset differential abstract tileimage can improve rotational correlation accuracy. To this end, creatingthe angularly offset differential abstract tile image can includerotating the existing abstract tile image by a small angle amount andsubtracting the resulting rotated abstract tile image from the existingabstract tile image.

FIG. 12A shows an example of a tile image 350 scanned in accordance withthe present invention. FIG. 12B shows a distribution curve 355corresponding to correlatable features (e.g., edges defining areas) ofthe scanned image 350. As can be seen, there are several correlationpeaks 360 of the distribution curve 355 on which to cross correlate. Thecorrelation peaks 360 correspond to high contrast points in the verticaldirection (i.e., in Y-direction) at a given horizontal position (i.e.,along X-axis). However, in view of such distribution of the correlationpeaks 360, it is possible to correlate the tile image 350 on a less thanoptimum or preferred correlation peak of the distribution curve 355.

As shown in FIG. 13A, through tile processing using means such as one ormore of those disclosed above in reference to steps 308-314, an abstracttile image 365 in accordance with the present invention can be derived.Through such processing, an abstraction of the tile image (i.e.,abstract tile image 365) is created for providing more predictable andprecise cross correlation. As can be seen, the distribution curve 370corresponding to correlatable features (e.g., edges defining areas)provides for more efficient, effective, and precise cross correlation inview of a single correlation peak 375.

Referring to FIG. 14, an angularly offset differential abstract tileimage 380 derived from the abstract tile image 365 of FIG. 13A is shown.The angularly offset differential abstract tile image 380 is useful indetermining angular rotation during cross correlation of two tileimages. The angularly offset differential abstract tile image 380 iscreated by rotating a copy of the abstract tile image 365 by a smallangle amount about a point of rotation 385 and subtracting the resultingrotated copy of the abstract image 365 from the original abstract tileimage.

FIG. 15 shows an embodiment of a method 400 for re-tensioning tiles of acomposite abstract image. Retensioning tiles is performed for optimizingplacement of tiles in a composite abstract image. Tiles within are-tensioned composite abstract image are selected and optimized tominimize discrepancies in alignment between adjacent tiles. As such, there-tensioned composite abstract image can be used for outputting ahigh-resolution image of scanned visual content from which the tiles aregenerated.

At an operation 402, the method 400 provides for determining potentiallyoverlapping tiles. The objective in determining potentially overlappingtiles is to provide a collection of potentially overlapping tiles basedon the best estimate of position and orientation. In one embodiment,such determination includes scan through tiles of the composite abstractimage determining their positions and extents (e.g., overall spatialdimensions) and calculating percentage of overlap between tiles that areclose enough in image space to possibly overlap. Next, an operation 404is performed for cross correlating all overlapping pairs of tiles. Crosscorrelation ascertains cross correlation in both translation androtation to determine translational and rotational correction needed toalign to pairs of image tiles. The image cross correlation between twooverlapping tiles determine the amount of translation or rotation thatis needed to best align those two tiles. This amount of translation androtation can be thought of as a tension between the two tiles. The crosscorrelation of a tile with all its the overlapping tiles creates a listof translations and rotations that if combined would produce atranslation and rotation for that tile that would best align with allthe overlapping tiles. It is disclosed herein that cross correlation oftile A with tile B can preclude needing to determine the crosscorrelation of tile B with tile A. After performing such crosscorrelation, an operation 406 is performed for determining tile positionadjustment necessary for minimizing discrepancies between crosscorrelation results. The objective of determining such adjustments is tominimize mis-alignment (i.e., tension) between the tiles such that anoverall average misalignment is minimized. In this manner, themisalignment tension between adjacent tiles is minimized. As each tile'sposition is adjusted, tension (i.e., misalignment) changes foroverlapping tiles. A ripple affect occurs through all the tiles in theimage as each tile's position and rotation are modified. In oneembodiment, minimizing overall tension in a composite abstract imageincludes iteratively determining translational and rotational positionof tiles and using the sum of the tensions and the change in the sum ofthe tensions to determine how many iterations were needed to settle on adesired solution. An operation 408 is performed for updating tilepositions based on the determined tile position adjustments. Afterupdating the tile positions, an operation 410 is performed for mergingthe tiles together into a high-resolution output image. Merge tilesincludes each new tile being added to a composite image as a weightedsum.

In one embodiment, the need for merging image tiles arises from suchimage tiles being an RGB image of pixel values. Associated with eachimage is a weight mask that that has a “goodness” value for each pixellocation. If the image is cropped by the housing of the unit, the partof the image containing the housing is no good for creating a compositeimage and is given a weight of zero. If glare from the LEDs, shadingaffects, or poor focus degrade part of the tile image, the weight maskis less than one. As each tile is added to the composite image, itspixel values are added in to the all the other images that have a pixelat that location in the universal (paper) space. The amount added fromthe new tile is proportional to the weight at that pixel locationcompared to the accumulated weight from all the previous tiles added tothe composite image at that same pixel location. So if the new tile hada weight for pixel being added of 0.84 and that pixel location in paperspace had an accumulated weight of 5.04, then 0.166 of the RGB pixelintensity of the current tile would be added to 0.833 of the previouslyaccumulated pixel intensity. To accomplish this, the merged compositeimage has a corresponding merged composite accumulated weight image.

FIG. 16 shows a method 500 for providing a feedback image in accordancewith an embodiment of the present invention. It is disclosed herein thatan area of a tile can be approximately the same as a scan area of thescanner that creates the tile. It is also disclosed herein that thephysical dimensions of a handheld scanner define a scan area of ascanner configured in accordance with the present invention. As such, itis often the case that capturing all desired visual content of ascannable object required that the scanner be repeatedly swept acrossthe scannable object until all desired visual content of the scannableobject has been scanned. Advantageously, a feedback image configured inaccordance with the present invention indicates areas of a scannableobject that have been scanned and those that have not. For example, inone embodiment, the feedback image displays portions of the visualcontent that are being scanned in real-time or near real-time as theyare being scanned. Thus, a user can use the feedback image as a guide toareas of the visual content that have yet to be scanned.

At an operation 502, the method 500 performs an operation for receivinga current sensor data instance. The current sensor data instanceincludes captured image data (i.e., a tile) and correspondinginterpolated position indicating data. In one embodiment, the currentsensor data instance is the processed sensor data instance produced inresponse to the operation 208 in FIG. 10A. After receiving the currentsensor data instance, an operation 504 is performed for using theinterpolated position indicating data to determine a position of thetile relative to other tiles already placed within universal image spaceof a feedback image, followed by an operation 506 being performed forcreating a preview image having the tile positioned therein. Creation ofthe preview image refers to transforming the composite abstract imagefrom universal image space to display space. Generally, the previewimage is not displayed, but is used in creating an image that isdisplayed for viewing (e.g., the feedback image). An operation 508 isthen performed for determining a scale factor to fit the tiles into aparticular display area (e.g., an area designated for displaying thefeedback image on a visual display of a computer). After determining thescale factor, an operation 510 is performed for quantizing the scalefactor to a predetermined display resolution, followed by an operation512 being performed for scaling the preview image. Quantizing the scalefactor refers to rounding or correlating the determined scale factor toa closest one of a plurality of pre-defined scale factor, whichadvantageously can control the resizing of the as-displayed feedbackimage. Next, an operation 514 is performed for determining areas of thepreview image for which there are no tiles positioned therein, followedby an operation for outputting a feedback image that includes visualindicators of unscanned areas and that includes shows visual content oftiles that have been generated. Because the feedback image is createdconcurrently with the visual content being scanned, visual content ofnewly scanned tiles is continuously being added to the feedback imageand the area of the feedback image corresponding to unscanned portionsof the visual content is continuously being populated with tiles duringa scan session.

Referring now to instructions processible by a data processing device,it will be understood from the disclosures made herein that methods,processes and/or operations adapted for carrying out sensor data capturefunctionality and/or image processing functionality as disclosed hereinare tangibly embodied by computer readable medium having instructionsthereon that are configured for carrying out such functionality(ies). Inone embodiment, the instructions are tangibly embodied for carrying outsensor data capture methodology as disclosed above in reference to FIGS.6-8. In another embodiment, the instructions are tangibly embodied forcarrying out image processing functionality in accordance with method200 disclosed above.). In still another embodiment, the instructions aretangibly embodied for carrying out sensor data capture methodology asdisclosed above in reference to FIGS. 6-8 and for carrying out imageprocessing functionality in accordance with method 200 disclosed above.The instructions can be accessible by one or more data processingdevices from a memory apparatus (e.g. RAM, ROM, virtual memory, harddrive memory, etc), from an apparatus readable by a drive unit of a dataprocessing system (e.g., a diskette, a compact disk, a tape cartridge,etc) or both. Accordingly, embodiments of computer readable medium inaccordance with an embodiment of the present invention include a compactdisk, a hard drive, RAM or other type of storage apparatus that hasimaged thereon a computer program (i.e., instructions) adapted forcarrying out sensor data capture functionality and/or image processingfunctionality in accordance with an embodiment of the present invention.

In the preceding detailed description, reference has been made to theaccompanying drawings that form a part hereof, and in which are shown byway of illustration specific embodiments in which the present inventioncan be practiced. These embodiments, and certain variants thereof, havebeen described in sufficient detail to enable those skilled in the artto practice embodiments of the present invention. Throughout thedescription and claims of this specification the word “comprise,”“includes,” or variations of these words are not intended to excludeother additives, components, integers or steps. It is to be understoodthat other suitable embodiments can be utilized and that logical,mechanical, chemical and electrical changes can be made withoutdeparting from the spirit or scope of such inventive disclosures. Toavoid unnecessary detail, the description omits certain informationknown to those skilled in the art. The preceding detailed descriptionis, therefore, not intended to be limited to the specific forms setforth herein, but on the contrary, it is intended to cover suchalternatives, modifications, and equivalents, as can be reasonablyincluded within the spirit and scope of the appended claims.

What is claimed is:
 1. An image capture unit, comprising: a positionindicating system configured for generating position indicating datainstances, wherein said position indicating data instances each includesdata derived from translational movement of the image capture unit andfrom rotational movement of the image capture unit; an imaging systemconfigured for capturing an image of visual content; and a dataprocessing arrangement configured for deriving from at least one of saidposition indicating data instances a position of the image capture unitat a point in time when a captured image data instance was one ofinitiated, completed, and partially completed, wherein deriving theposition of the image capture unit includes interpolating the positionof the image capture unit from at least one of said position indicatingdata instances generated prior to a point in time when the capturedimage data instance was one of initiated, completed, and partiallycompleted and at least one of said position indicating data instancesgenerated after the point in time when the captured image data instancewas one of initiated, completed, and partially completed.
 2. The imagecapture unit of claim 1 wherein the interpolating of the position of theimage capture unit includes determining a timeline offset dependent uponcreation time information of said position indicating data instances andcreation time information corresponding to the point in time when thecaptured image data instance was one of initiated, completed, andpartially completed of the captured image data instance.
 3. The imagecapture unit of claim 1 wherein the deriving of the position of theimage capture unit includes using a plurality of said positionindicating data instances to determine momentum of the image captureunit and using said momentum to determine the position of the imagecapture unit at a point in time when the captured image data instancewas one of initiated, completed, and partially completed.
 4. The imagecapture unit of claim 1 wherein the position indicating system includesat least one of: a plurality of spaced apart sensors each configured forsensing translational velocity of the image capture unit; a sensorconfigured for sensing rotational movement of the image capture unitabout a rotational axis; and a sensor configured for sensingtranslational acceleration of the image capture unit.
 5. The imagecapture unit of claim 1 wherein the imaging system includes an arraysensor configured for digitizing an area of said visual content.
 6. Theimage capture unit of claim 5 wherein the position indicating systemincludes at least one of: a plurality of spaced apart sensors eachconfigured for sensing translational velocity of the image capture unit;a sensor configured for sensing rotational movement of the image captureunit about a rotational axis; and a sensor configured for sensingtranslational acceleration of the image capture unit.